David Cameron is visiting Glasgow four months ahead of the independence referendum (Picture: Getty Images)

David Cameron has invoked the memory of former Labour leader John Smith as he campaigns to keep Scotland in the United Kingdom.

The Tory prime minister hailed Mr Smith – who died 20 years ago – as a ‘proud Scot’ who wanted what was best for his country.

Crucially, he said the former Labour leader understood that ‘wanting to be part of something bigger does not make you any less Scottish’.

Mr Cameron is embarking on a two-day campaign trip to Scotland four months ahead of September’s independence referendum, when voters north of the border will be asked whether they want Scotland to remain in the UK.

The Conservative leader will use the visit to make the positive case for the union, meeting and speaking to people in Glasgow today.

He insisted his message for voters in the referendum is simple: ‘We want Scotland to stay.’

But Scotland’s deputy first minister Nicola Sturgeon said the trip north is part of a ‘wholesale Tory takeover’ of the campaign to keep Scotland in the UK, warning this could prove ‘disastrous’ for those opposed to independence.

While the No campaign is still ahead in the polls, some surveys have suggested the gap is narrowing.

Despite that, Mr Cameron insisted people from ‘all walks of life and all parts of the UK know, as I know, that we are all better together’.